Safety scalpel

Abstract

A scalpel enabling both safe blade engagement or disengagement and safe passing among personnel during surgical procedures. The blade arm assembly of the scalpel is positionable in three positions, including a retracted position, an operational extended position and a fully extended position for engagement and disengagement of the blade.

The invention claimed is:  
     
       1. A scalpel handle assembly for use with a replaceable scalpel blade, the assembly comprising:
 (a) a handle comprising an elongated body, a central channel slot, a pair of opposed transverse slots, a first detent, and a second detent, and 
 (b) a blade arm assembly comprising:
 (i) a button assembly comprising a button and a pin, and 
 (ii) a blade arm comprising a blade tang positionable relative to the handle alternatively:
 (1) with the pin of the button assembly received in the first detent wherein the blade is withdrawn entirely into the handle, 
 (2) with the pin of the button assembly received in the second detent wherein the blade projects from the handle with the base of the blade captured in the pair of opposed transverse slots thereby retaining the blade on the tang, wherein the blade is locked in position and operational, or 
 (3) with the pin of the button assembly extended beyond the second detent wherein the blade is entirely outside the handle with the base of the blade extended beyond the pair of opposed transverse slots wherein the blade is not secured to the blade arm, and wherein the blade is removable without contacting the blade, 
 
 
 (c) wherein a first transition between the first detent and a side of the central channel slot is more gradual than a second transition between the second detent and the side of the central channel slot requiring an increased lateral force to disengage from a blade projecting position to a fully projected position for removing the blade from the blade tang, 
 (d) wherein depression of the button permits advancement and retraction of the blade arm assembly. 
 
     
     
       2. A scalpel handle assembly for use with a replaceable scalpel blade, the assembly comprising:
 (a) a handle comprising an elongated body penetrated by a first longitudinal slot open to the outside of the handle, and a pair of opposed transverse slots perpendicular to the first slot, and 
 (b) a blade carrier assembly comprising:
 (i) a blade arm comprising a blade tang attached to an arm body positionable within the first slot, and 
 (ii) a spring associated with the blade arm to secure the blade arm in a selected one of two positions with a blade projecting from the handle for use or retracted into the handle for safety; 
 
 (c) wherein a pin is received in a first detent when the blade is projecting from the handle for use; 
 (d) wherein the pin is received in a second detent when the blade is retracted into the handle for safety; 
 (e) wherein a first transition between the second detent and a side of the first slot is more gradual than a second transition between the first detent and the side of the first slot requiring an increased lateral force to disengage from a blade projecting position to a fully projected position for removing the blade from the blade tang. 
 
     
     
       3. The scalpel handle assembly of  claim 2 , wherein a button or knob facilitates manipulation of the pin. 
     
     
       4. The scalpel handle assembly of  claim 2 , wherein the pin is secured to the spring and is received in one of the two detents in the handle. 
     
     
       5. A surgical scalpel comprising:
 (a) a blade arm assembly that slides within a handle, wherein the blade arm assembly comprises a blade arm, a button assembly and a spring, the spring comprising a bi- cantilever element, 
 (b) the handle comprising a pair of transverse slots that receive the blade arm assembly, wherein a blade is secured to the blade arm assembly by a portion of the blade attached to the blade arm assembly being captured in the pair of transverse slots, 
 (c) wherein the blade is secured to the blade arm assembly in one of two positions:
 (i) a fully retracted position with the entire blade withdrawn into the handle, or 
 (ii) a protruding operational position with a base of the blade captured in the pair of transverse slots with a cutting edge of the blade projecting from the handle for use, and 
 
 (d) wherein the blade is positionable in a fully extended position for engaging and disengaging the blade with the base of the blade extending beyond the pair of transverse slots such that the blade is removable from the blade arm assembly without contacting the blade and 
 (e) wherein a free end of a first cantilever section of the bi-cantilever element is shaped to fit around a curved end of a second cantilever section of the bi-cantilever element, thereby allowing for a spring-like action limited in its inward travel by the contact of the two cantilever sections as they are squeezed toward each other.